Vania



(No Model.) 2 Sheets-Sheet 1. W. STANLEY, Jr.

REGULATION OF ELEGTRIG MOTORS. No. 392,890. Patented Nov. 13, 1888.

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Parana? \VILLIAM STANLEY, JR. OEGREAT BARRINGTON, MASSACIIUSETTS, ASSIGEOR TO THE WESTINGHOUSE ELECTRIC GOMPAN OF PITTSBURG, PENNSYL VANIA,

SPECIFICATION forming part of Letters Pat iC OTORS.

ent No. 392,89 dated Elovernber 13, 1888.

Application filed May 13, 1837. Serial No. 938,135, (No model.)

To aZZ whom it may concern:

Be it known that I, \VILLIAM STANLEY, Jr., a citizen of the United States, residing in Great Barrington, in the county of Berkshire and State of Massachusetts, have invented certain new and useful Improvements in the Method of Regulating Electric Motors, of which the following is a specification.

In the accompanying drawings, which make IO part of this specification, Figure 1, Sheet 1, is a diagrammatic view of an electric motor and a regulating apparatus illustrating the application of my invention when a constant quantity of current is supplied; Fig. 2, Sheet 2, a similar View illustrating the application when a constant difference of potential is supplied; and Figs. 3 and i, similar views exemplifying modifications in the arrangement of the demagnetizing-circuit.

The object of my invention is to effect the regulation of an electric motor to a determined constant speed, as may be required by the work to be performed by the motor, so as to prevent variation of speed under increase or diminution of duty or load.

To this end my invention, generally stated, consists in a novel method of increasing and decreasing the development of energy from an electric motor in accordance with and proportionately to variations in the work or load imposed by automatically decreasing and increasing the electromagnetic effect of a demagnetizing-circuit upon the field of the machine.

In the operation of electric motors it is desirable, and in many cases essential to a proper and effective performance of their work, that a uniform speed should be maintained irrespective of the temporary variations in the re sistance imposed by the partial cessation or the additional imposition of work, as in the case of the illumination of a greater or less number of electric lights or the operation of more or less machinery from time to time. Motors employed in such service may be operated under either of two different conditionsfirst, where the electric energy actuating the motor is supplied as a constant quantity of current flowing through a line, in which case the electro-motive force applied to the terminals varies as the work performed; and,

second, where constant eleetro'motive force or difference of potential is applied to the terminals of the motor, in which case the quan tity of current flowing through the motor will be varied proportionately with variations in the work.

My invention, which is equally applicable under-either of the abovestated conditions, affords ready and effective means for insuring the maintenance of such speed of the motor as may be suitable or requisite for the performance of the particular duty to which it is as- Signed.

Referring first to the case of a motor adapted to use in a line supplied with a constant quantity of current, Fig. 1 illustrates a construction adapted to the practice of my invention. The motor, which may be of any suitable and preferred construction, is here shown as provided with magnet-cores 10 ll, provided with pole-pieces 12 10, between which an armature, 14, is adapted to rotate in the usual manner. The electric current which actuates the motor passes from a generator or other suitable source of supply through an energizing-circuit composed of a wire, 1, connected to one of the terminals S, a wire, 2, wound upon the magnetcores 10 ll, and leading from the terminal 8 to one of the brushes 1:; of the armature 14, a wire, 3, wound around a regulating electro- 8c magnet, 4,and extending from the other brush, 16, to the opposite terminal 9, and a wire, 5, leading from the terminal 9 to the generator. A deniagnetizing-circuit, which is practically a shunt across the terminals of the motor, is formed by a finer wire, 6, leading from the terminal 8 and wound around the magnet-cores 1O 11 to a connection with a resistance line or coil, 7, from which a series of connecting-wires, 17, extend at different points in its length to contact-plates 18. The demagnetizing-circuit on the opposite side of the resistance line or coil 7 extends through an automatic switchlever, 20, pivoted at one end by a link, 23, to the armature 22 of the regulating-magnet 4, and adapted to make contact, as raised or lowercd by the movements of the armature, with either of the different contact-plates 1S, and wires 2i 25 lead from the switch-lever 20 to the terminal 9 of the motor. The fine wire of r00 the demagnetizing-eircuit is of comparatively high resistance relatively to the coarser wire of the energiziugcircuit, and consequently takes a smaller portion of the current, and when the motor is in motion the quantity of current flowing through the demagnetizingcircuit is proportional to the counter electromotive force of the motor, and the resistance of the energizing-circuit is less than that ol' the demagnetizing-circuit. \Vhen the current is turned on the motor from the generator, the regulating-magnet at raises the switch-lever 20 and holds it with its free end in contact with the plate 18, which is connected with the farther extremity of the resistance-line 7 thereby throwing a maximum of resistance into the demagnetizingcircuit until the motor has obtained, through the revolutions of its armature, sufficient counter electro-motive force to cause the resistance of the energizing-circuit through the wires 2 3 to exceed that of the demagnctizingcircuit through the wire 6, resistance-line 7, connection 17, contact-plate 1S, switch-lever 20, and wires 2t 25. Such increase of resistance, by deinagnetizing the regulating-magnet 4, allows the switch-lever 20 to fall back to the position shown in the draw ings, in which the minimum of resistance is shunted into the demagnetiZing-circuit and the dcmagnetizing effect of said circuit is at its maximum, such demagnetizing effect tending to reduce the counter electro-motive force by demagnetizing the field of the motor-magnet.

It now a load be added, the amount of current ilowingthrough theenergizing-cireuit will be increased by reason of the decrease of counter elcctro-motive force due to the slowing up of the armature. This increase of current excites the regulating-magnet t and causes it to lift the switch-lever 20, thereby increasing the resistance of the demagnetizing-circuit by throwing in a greater length of the resistance line or coil 7, such increase of resistance correspondingly increasing the speed of the motor both by reason of the decrease of the demagnetizing effect of the demagnetizing-circuit, and of the increase of the magnetizing effect of the energizing-circuit due to the arrangement oi. the two circuits as shunts to each other. The movement of the switch-lever in the direction to increase resistance continues until the counter elcctro-motive force has risen sufficiently to decrease the quantity of current through the energizingcircuit and thereby to stop the upward pull oi the magnet. If, on the other hand, the mechanical load be decreased, the revolutions of the armature will be momentarilyincreased, the counter electromotive force will be increased, and the regulating-magnet 4 will thereby be weakened. The resistance of the demagnetiZing-circuit will consequently be decreased by the lowering of the switch-lever and a greater quantity of current be permitted to flow through said circuit,such increase of current demagnetizing the magnets of the motor and reducing its speed to the degree required.

Fig. 2 illustrates a construction applicable in cases where a constant difference of potential between the terminals 8 9 of the motor is employed. The current of the energizing-circuit passes through the wire 1 to the terminal 8 of the motor, thence through the wire 2, wound upon the magnet-cores 10 1l,to one of the brushes 15, and from the other brush, 16, through a wire, 3, wound upon the regulatingmagnet 4, to a connection, 26, at which it is divided, a portion passing through a demagnetizing-circuit composed of a wire, 27, lead ing to a binding-post, 28-, on the motor, and a wire, 6, leading from thebinding-post 28 to the terminal 9 and wound upon the magnet-cores 10 11. The other portion of the current passes as a shunt to this circuit having a variable resistance formed by the wire 29, switch-lever 20, contact plates 18, connections 17, resistance line or coil 7,and wire 30.

When current is not turned on to the motor, the armature of the regulating-magnet not being attracted the connected end of the switchlev'er is in its lowest position, as shown in the drawings, and consequently the maximum resistance is thrown into the shunt-circuit.

Upon the application of a current to the mot0r,the regulating-magnet 4,being exeited,lifts the switch-lever 20 and by cutting out a portion of the variable resistance allows a greater quantity of current to flow through the shuntcircuit wires 29 30 to the terminal 5 and a less quantity through the demagnetizing-circuit, and the motor consequently increases its speed until the counter electro-motive force rises sufficiently to reduce the strength of the regulating-magnet and. increase the resistance of the shunteircuit to the required degree. Under such construction the strengthening of the regulating-magnet cuts out resistance in lieu of throwing in resistance, as in the case first described, but in both the same resultto wit, the reduction of the effect of the de magnetizing circuit is attained by the strengthening of the magnet.

IIO

It will be obvious that the arrangement of circuits may be modified in sundry partieulars without departing from the spirit ofmy invention so long as a regulating-magnet and variable resistance are employed to vary the field-strength of a motorby varying thestrength of a demagnetizing-current-as, for example, the regulating-magnet may be arranged in the direct circuit of the motor, in shunt to the motor or in shunt to the armature of the motor.

In Figs. 3 and 4 the regulating-magnet is connected in shunt to the armature of the motor by wires 83, and the demagnetizing-circuit and its variable resistance is arranged in Fig. 3 as a shunt to the terminals of the motor, and in Fig. 4 as a shunt to the terminals of the armature. In each case the magnetic strength of the regulating-magnet increases when the counter electro-motive force of the armature is highest, whilein the construction shown in Figs. 1 and 2 the magnetic strength of the regulating-magnet decreases when the counter electromotive foreeis highest. Again, in Fig. 3 the upward movement of the armature of the regulating-magnet decreases the variable resistance, While in Fig. 1 the upward movement of said armature increases the variable resistance.

The specific regulating mechanism herein shown does not per 80 constitute part of my present invention, and need not therefore be at length described, as other devices may be equivalently employed in the practice of my invention to attain the result effected thereby. Said mechanism, moreover, constitutes the subject-matter of another application for Letters Patent filed by me.

I claim as my invention-- The improvement in the method of regulating the speed of electric motors,vvhieh consists in automatically varying the eleetro-mag- 2o neticeffectofa demagnetizing-current upon the field of the motor by introducing variations of resistance in said circuit coincidentl y with and proportionately to variations in the mechanical duty of the motor,substantially as set forth.

2. The hereinbefore-described method of 25 governing electromotors, which consists in automatically varying the current traversing a demagnetizing-circuit applied to the field-magnet of the motor by varying the resistance of said circuit coincidently with and propertionately to variations in the mechanical duty of the motor.

In testimony whereof I have hereunto subscribed my name this 30th day of April, A. D. 1887.

WILLIAM STANLEY, JR.

Witnesses:

FREDERICK N. DELAND, CHAS. M. Gums. 

